Try reseating the connectors on the auxiliary transmission pump at the front of the transmission and also at teh transmission pump control module under the hood just right and down from the battery. My Yukon was doing a similar thing twice over the last 40k miles and reseating the wiring connectors instantly fixed it both times. The issue for me is if you replace either the pump or module, you have to do both if an 08 or 09 because they have a different connection between them and only 2010 and newer parts are available. I didn't want to replace both so I tried the reseating thing and its worked both times (fingers crossed) I don't mind really buying the new parts but you have to have the module programmed to fit your application (dealer thing).

 

Well, I think my problems are solved - for now. But that's good info to have stored in my think tank.


Thanks for the knowledge share!

 

Does the auxiliary transmission pump use the same fluid resevoir as the main transmission?

 

Yes same oil pan. However the pump has its own filter and riser tube. Both filters have a riser tube and "O" ring.


And just like any hydraulic automatic... if that "O" ring leaks you suck air. = BAD

 

Am I reading this correct that you need to replace the aux trans pump module & the aux trans pump at the same time? Not one at a time to see which is causing the issue?

 

 

Should the wiring connector be cleaned with plastic safe electrical contact cleaner and then receive a layer of dieelectric grease before reseating? or just unplug and plug back up? Just wondering what worked best? I had a taillight bulb connector that required some additional effort over just resetting the bulb.....